Medium-chain fatty acids and their metal salts are non-toxic materials which are used in the food and pharmaceutical industries. According to part 184 of the Code of Federal Regulations (CFR), the US Food and Drug Administration (FDA) has granted the medium-chain, C8 fatty acid, caprylic acid or octanoic acid, a GRAS (Generally Recognized As Safe) affirmation. Similarly, according to part 172 (CFR) free fatty acids (e.g., caprylic acid, capric acid, lauric acid) and their metal salts, are recognized as safe additives for use in food. As noted by Dimitrijevic et al, Journal of Pharmacy and Pharmacology 53:149-154 (2001), the sodium salt of the medium-chain, C10 fatty acid, capric acid or decanoic acid, is approved for human use in Sweden and Japan as an absorption enhancer for rectal drug products.
WO02183120 discloses that medium-chain fatty acids and their metal salts (especially capric acid, caprylic acid and their sodium salts) are able to induce hematopoiesis. The sodium salts of capric acid and caprylic acid, in comparison to the respective free acids, possess superior water solubility. The solubility of capric acid is 15 mg/100 g water (20° C.) whilst that of caprylic acid is 68 mg/100 g water (20° C.).
Typically, the reaction of an acid with base in an aqueous medium is rapid and straightforward, as long as the acid and base are water-soluble. The limited water-solubility of medium-chain fatty acids makes the large-scale, high-yield preparation of the metal salts of fatty acids more difficult. Emulsions and suspensions can form, with excessive frothing and foam if carbon dioxide is a byproduct of the reaction (e.g., use of bicarbonate or carbonate base).